Response of American lobsters Homarus americanus to infection with a field isolate of Aerococcus viridans var. homari (Gaffkemia): survival and haematology

American lobsters Homarus americanus were inoculated with a field isolate of the Gram-positive bacterium Aerococcus viridans var. homari, causative agent of gaffkemia, at 1 x 10(6), 1 x 10(4) or 1 x 10(2) colony forming units (CFU) kg(-1) or with sterile 3% NaCl and maintained at 10 or 15 degrees C until they died or were euthanised. Progression of disease in individual animals was monitored daily by total haemocyte count (THC) and haemolymph culture. Post-mortem examinations were performed on all lobsters. Effects of both ambient temperature and infective dose on survival time were observed. Marked bacteraemia occurred in all mortalities. Haemocytopenia (THC < 10 x 10(9) cells l(-1)) preceded death in most, but not all, mortalities.